Action for pneumatic piano-players.



No. 892,400 PATENTED JULY 7, 1908.

E. OARLSON. ACTION FOR PNEUMATIC PIANO PLAYERS.

APPLICATION FILED PEB.18,1907.

a SHEETFSHEET 1.

2x3 in eases No. 892,400. PATENTED JULY '7, 1908. E. OARLSON. ACTION FORPNEUMATIG PIANO PLAYERS.

APPLICATION FILED FEB. 18,1907.

3 SHEETS-SHEET 2.

' PATENTED JULY 7, 1908. E; OARLSON. ACTION FOR PNEUMATIC PIANO PLAYERS.

APPLICATION FILED PEB.18.1907.

3 SHEETS-SHEET a.

' wozntoz Wit eons ERICK GARLSON, OF CHICAGO, ILLINOIS.

ACTION FOR, PNEUMATIC PIANO-PLAYERS.

Specification of Letters Patent.

Patented July 7, 1908.

Application filed February 18, 1907. Serial No. 357,908.

To all whom it may concern:

Be it known that I, Enron CARLSON, a citizen of the United States, residing at Chicago, in the county of Cook, State'of Illinois, have invented certain new and useful Improvements in Actions for Pneumatic Piano-Players; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to pneumatic actions for pneumatic piano players and the object of the invention is to provide a very simple form of action which will act quickly both to strike and release the keys.

The further object of the invention is to provide means whereby the primaries will be relieved of any undue pressure, this object being attained by providing a return duct from each primary for the escape of surplus air. The provision of this duct permits quick return of the primary after being actuated and consequently a quick release of the key of the piano.

My pneumatic action is designed particu larly for use in connection with detached piano players although it will be understood of course that it may be employed in a combined piano and player without departing from the spirit of the invention.

Inthe accompanying drawings, Figure 1 is a rear elevation of a pneumatic action constructed in accordance with my invention, Fig. 2 is an end elevation thereof, Fig. 3 is a front elevation but showing a portion of the casing broken away, Fig. 4 is a view in elevation of the rear of the pneumatic action with the rear wall of the casing partly broken away, Fig. 5 is a detail vertical sectional view taken centrally through the action, and, Fig. 6 is a detail horizontal sectional view.

Referring more specifically to the drawings my invention is shown as comprising a vacuum chest having front and back walls 10 and 11 respectively and the chest is closed on all sides. The rear wall of the chest has its forward face dished or recessed as at 12, wherever one of the pneumatic actions is to be located and over each recess is stretched a diaphragm 13 which forms the primary pneumatic. For convenience sake only one of the pneumatic actions will bedescribed as they are all of the same construction. An arm 14 has its lower end turned laterally as at 15 and engaged in a groove 16 formed in a block 17 which is secured to the said forward face of the rear wall ofthe chest. From its cranked portion 1 5 the arm 14 extends vertically across the diaphragm 18 and through a guide 18 Which is secured upon a disk 19 upon the dia phragm 13. The upper end portion of the arm 14 is turned rearwardly as at 20 and screw threaded and engaged upon the said threaded portion of the arm forward of the wall 11 is a disk valve 21 which serves to close at times an opening 22 formed through the said wall and through which. opening the threaded portion 20 of the arm projects. A

similar disk valve 23 is also engaged adjustably upon the threaded portion 20 of the arm 14 and this valve, as in the case of the valve 21, also serves to close the opening 22.

Formed in the rear wall is a transversely extending passage way 24 which has communication with the interior of the chest as indicated at 25. The purpose of this passage way will presently be stated.

Leading into the chest through the rear wall thereof and having communication with the recesses 12 therein are air ducts 26 which lead from the orifices in the usual tracker board for the purpose of admitting air to the primary pneumatics when the o enings in the music sheet pass over the ori 'ces in the board. Now in order to prevent the accumu lation of air in the primaries and to vent the same, a short duct 27 leads from each primary into the passage way 24 and, having a bore of slightly less diameter than the bore in the duct 26, it permits the slow eXhaushor bleeding of air from the primary.

A number ofpassageways 28 are formed through the top of the chest and communicate one with each opening 22, and upon the said top of the chest is arranged a series of operating pneumatics 29 which are in communication with the passage ways 28 and which carry the usual key operating jacks 30. An opening 31 is formed through one side of the chest and serves as a means whereby the air may be exhausted.

The operation of my pneumatic action is as follows: It is to be understood of course that there is a vacuum normally maintained within the chest. Now when air is admitted through one of the ducts 26 by the registration of one of the openings in the music sheet with the corresponding orifice in the tracker board, the corresponding primary pneumatic will be operated to cause the valve 23 to close the opening 22 to the atmosphere and open valve 21 to put the operating pneumatic 29 in communication with the chest by way of the said opening 22. This will result in the collapse of the operating pneumatic owing to the fact that there is a vacuum in the chest, thereby striking the corresponding piano key.

What is claimed is- A pneumatic action of the class described comprising a vacuum chest, a primary arranged within the chest, an air duct communicating with the primary, an operating pneumatic arranged upon the chest, there being a passage way formed through that wall of the chest upon which the primary is located and a passage way formed througl'i the said wall and establishing communication between the lust mentloned passage way and the operating pneumatic, a lever mounted for rocking movement upon the said wall of the chest and within the chest and extending across the primary and connected with the diaphragm thereof, a valve-stem integrally connected with said lever and extending through the first mentioned passage way and outwardly of the chest, and valves adjustable upon said stem, one of said valves being located within the chest and the other outwardly of the same, there being a bleed duct in communication with the said primary and opening into the atmosphere.

In testimony whereof, I allix my signature, in presence of two witnesses.

ERICK (1A RLSON.

itnesses ANDREW G. CARLSON, CHARLES VICTOR STONE. 

